A production SQL Anywhere 12 High Availability exists using the old-school command line methods:
dbsrv12 ... -xp partner=(eng=xxx;links=tcpip(host=192.168.0.20; ...
Can the new CREATE MIRROR SERVER and SET MIRROR OPTION statements be added to this setup to implement a read-only scale-out copy node?
Or does the existing High Availability setup have to be changed to use the new-school CREATE MIRROR SERVER methods?
No, you cannot use -xp specified partners with copy nodes.
What you need to do is:
Note that mixing CREATE MIRROR SERVER definitions with old (deprecated) -xp key=value;... definitions can lead to unexpected behavior so they should not be mixed.